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The optical elements of NIRI (e.g. cameras, filters, grisms and slits) are described in detail on the NIRI pages.
The filter menu is divided into broad- and narrow-band filters, in order of increasing wavelength. For spectroscopy, select the "grism order sorting" filter from the menu, the appropriate grism (disperser) and slit.
The ability of the AO system to correct the wavefront depends on the brightness and off-axis angle of the wavefront reference source (the AO "guide star"). The Strehl ratio of the AO-corrected core is approximated in the ITC by:
Changes included in the v2.0 releases (issued 8 March 2002) are listed below.
Changes and bugs (coded red, or black if fixed) within the Integration Time Calculator are listed below. See the main ITC page for a list of the most recent changes.
There are two modes available:
- Calculate the total signal-to-noise ratio (S/N) for an observation with the specified exposure time, number of exposures and sky subtraction method
- Calculate the total integration time to achieve the requested S/N for an observation with the specified exposure time and sky subtraction method
Each new calculation will post results into the same page. The results page can be printed and re-sized e.g. so that the ITC form and results are both visible on your screen.
Additional information is available for:
22 Feb 2006
28 Feb 2005
It has recently been determined that all spectral flats using the low resolution 10um grating obtained prior to Feb 27, 2005 were saturated. This means that:
- all unratioed spectra that have been flatfielded prior to then have incorrect spectral shapes;
- all spectra of extended sources that were ratioed by spectra of a point source (std) have incorrect shapes.
These differences are not huge, but are noticeable.
The following letter is being circulated to the Gemini community as of September 14, 2004.